This invention relates to a packaging machine of the type having a pouch making section for forming an elongated strip of interconnected pouches from a flexible web and further having a pouch filling section for filling and sealing the pouches after the pouches have been severed from the strip at the downstream end of the pouch making section. The machine of the invention preferably is of the intermittent motion type in which the web and the pouches are advanced intermittently or step-by-step and in which the pouch forming, filling and sealing operations take place when the web and the pouches dwell between successive steps.
It is well recognized in the packaging machine art that pouches can be made at a much faster index cycle rate than the pouches can be filled since a relatively long dwell period is required to fill the pouches. Even if multiple filling mechanisms are used to fill each pouch during successive dwell periods, the pouch filling section of a standard packaging machine must run at the same index cycle rate as the pouch making section. While the dynamic considerations involved in running the pouch making section at a high index cycle rate can be dealt with, the dynamic factors involved in running the pouch filling section at the same high cycle rate present a much more difficult problem.
In order to overcome that problem, efforts have been made to reduce the index cycle rate of the pouch filling section while still enabling that section to accommodate the entire pouch output of a high speed pouch making section. For example, Loomis, Jr. et al U.S. Pat. No. 3,762,253 discloses a dual lane packaging machine in which pouches made at a high rate by a pouch making section are divided into two laterally spaced rows for advancement through the pouch filling section. While this arrangement allows the pouch filling section to run at one-half the index cycle rate of the pouch making section, the dynamic and cost considerations of dividing the pouches into two laterally spaced rows constitute a significant drawback.
Another example of a relatively low index cycle rate but relatively high output machine is a model BMR 200 machine marketed by the Bosch Packaging Machinery Division of Robert Bosch GmbH. In that machine, pouches are made two at a time and then are indexed in such a manner as to enable the pouches to be filled and sealed two at a time. While this enables both the pouch making section and the pouch filling section to operate at an index cycle rate equal to one-half the total pouch output rate, duplicate pouch making mechanisms are required, thereby increasing the cost of the machine. In addition, the pouch web must be fed in relatively long lengths equal to the width of two pouches and thus control over the web is reduced and particularly when the pouches are cut from the strip.